Evaluation of mTOR signaling pathway in premalignant and malignant cervical lesions.Correlation with HPV infection

Doctoral Dissertation uoadl:1308527 132 Read counter

Unit:
Τομέας Υγείας - Μητέρας - Παιδιού
Library of the School of Health Sciences
Deposit date:
2014-05-12
Year:
2014
Author:
Ανδρικοπούλου Mαρία
Dissertation committee:
Κρεατσάς Γεώργιος, Δεληγεώρογλου Ευθύμιος, Σαλάκος Νικόλαος, Δενδρινός Σπύρος, Ρίζος Δημήτριος, Κόνδη-Παφίτη Αγάθη, Μιχαλά Σταυρούλα
Original Title:
Mελέτη της σηματοδοτικής οδού mTOR σε προκαρκινικές και καρκινικές βλάβες του τραχήλου της μήτρας. Συσχέτιση με την παρουσία στελεχών του ιού ΗPV
Languages:
Greek
Translated title:
Evaluation of mTOR signaling pathway in premalignant and malignant cervical lesions.Correlation with HPV infection
Summary:
Introduction: Squamous cell carcinoma (SCC) of the uterine cervix is the most
common malignant tumour of the genital tract worldwide. The association between
certain oncogenic (high-risk) types of HPV and cervical cancer is well
established and HPV infection accounts for 99.7% of cervical cancers. The
mammalian target of rapamycin (mTOR) is a serine/threonine protein kinase which
regulates cell growth, proliferation and protein synthesis. Aberrant activation
of upstream and downstream molecules of the Akt/mTOR/pS6 signaling pathway has
been identified in various types of human cancer. The serine/threonine kinase
mTOR pathway is an appealing therapeutic target because of the availability of
potent inhibitors such as rapamycin and its analogues which have been utilized
in clinical trials for metastatic renal cell carcinoma and hematologic
malignancies. However, the exact role of mTOR signaling pathway in cervical
cancer not fully understood and is currently under investigation.
Purpose: The purpose of this study was to assess the expression of the
phosphorylated (activated) forms of Akt, which is an upstream molecule of the
pathway and 4E-BP1 and pS6, both downstream molecules, in biopsy samples of
cervical a) Low Grade Squamous Intraepithelial Lesions (LSIL), b) High Grade
Squamous Intraepithelial Lesions (HSIL) and c) Squamous Cell Carcinoma (SCC)
compared to d) normal cervical epithelium. In addition identification of HPV
types in all four groups was attempted and the possible interaction between HPV
infection and m TOR signalling pathway was studied.
Material and Methods: Ninety eight tissue samples from patients diagnosed with
premalignant and malignant cervical lesions were studied. 38 cases were
diagnosed as LSIL, 31 cases as HSIL and 29 cases as SCC of the cervix. Eight
control cases from normal cervix were also included in the study.
Immunohistochemistry was used to assess the expression of p Akt, p 4E-BP1 and
phospho pS6. Immunohistochemical reactivity for all 3 molecule was graded in a
semi-quantitative manner. Moreover, a combined score of immunohistochemical
positivity (0, 2-6) was calculated for each case by adding the individual
scores for percentage of cells (0-3) and intensity of staining (0-3).
Additionally, PCR for 35 clinically relevant High Risk (HR) and Low risk (LR)
HPV types was performed in all cases studied to identify possible HPV
infection.
Results: Statistical analysis revealed significant differences between each
study group (HSIL, SCC) and controls regarding intensity (p<0.001), positivity
and total scores (p<0.0001) for all 3 molecules. In addition possible
correlation between the 3 molecules in all cervical lesions was assessed in
terms of percentage of positive cells, intensity of immunoreactivity and total
scores using Kendall’s tau test. All molecules were positively correlated to
each other, as expected since they all serve as upstream and downstream
effectors of the same signalling pathway. Furthermore an increasing trend in
intensity, percentage of positive cells as well as total score with increasing
grade of dysplasia was observed in all cases at a statistically significant
level.
Possible correlation between HPV infection and m TOR signaling pathway was also
assessed. Correlation between the expression of the 3 molecules (Akt, 4E-BP1,
pS6) was studied in the following groups a) HPV negative cases, b) LR HPV
positive cases c) HR HPV positive cases. Τhe expression of pS6 molecule was
significantly increased in HPV HR positive compared to HPV negative cases
whereas regarding the other 2 molecules there was an increased expression in
HPV positive cases which was not however statistically significant.
Conclusion: This is the first report to demonstrate up regulation of the 3
upstream and downstream molecules of mTOR signaling pathway in premalignant and
malignant cervical lesions as well as an increasing trend in intensity,
percentage of positive cells as well as total score with increasing grade of
dysplasia at a statistically significant level. These results taken together
strongly support the view that the mTOR signaling pathway is involved in
cervical carcinogenesis even in the early stages. Additionally, our results
suggest a possible interaction between HPV related carcinogenesis and mTOR
pathway. Further studies assessing the activation of additional down and
upstream molecules of mTOR in relation to HPV infection may shed more light
into the molecular mechanisms underlying cervical carcinogenesis.
Keywords:
mTOR signaling pathway, HPV infection, Cervical cancer, Rapamycin
Index:
No
Number of index pages:
0
Contains images:
Yes
Number of references:
223
Number of pages:
131

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